Method for manufacturing optical device, optical device, and biological information detector

ABSTRACT

A biological information detector includes a substrate, a light-emitting element, a light-receiving element, and a bonding pad. The light-emitting element has a thickness of 20 μm to 1000 μm. The light-receiving element has a thickness of 20 μm to 1000 μm. The bonding pad is disposed at a position that overlaps the light-emitting element and that is displaced relative to a center of the light-emitting element in a plan view as viewed in a perpendicular direction perpendicular to an emitting surface of the light-emitting element. A wavelength of light emitted by the light-emitting element is within a range of 470 nm to 600 nm.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. patent application Ser. No.13/022,177 filed on Feb. 7, 2011. This application claims priority toJapanese Patent Application No. 2010-033058 filed on Feb. 18, 2010. Theentire disclosures of U.S. patent application Ser. No. 13/022,177 andJapanese Patent Application No. 2010-033058 are hereby incorporatedherein by reference.

BACKGROUND

1. Technical Field

The present invention relates to a method for manufacturing an opticaldevice, an optical device, a biological information detector, and thelike.

2. Background Technology

A biological information measuring device measures human biologicalinformation such as, for example, pulse rate, blood oxygen saturationlevel, body temperature, or heart rate, and an example of a biologicalinformation measuring device is a pulse rate monitor for measuring thepulse rate. Also, a biological information measuring device such as apulse rate monitor may be installed in a clock, a mobile phone, a pager,a PC, or another electrical device, or may be combined with theelectrical device. The biological information measuring device has abiological information detector for detecting biological information,and the biological information detector includes a light-emittingelement for emitting light towards a detection site of a test subject(i.e., a user), and a light-receiving element for receiving light havingbiological information from the detection site. Thus, a biologicalinformation detector or the biological information measuring device mayhave an optical device and be capable of detecting or measuringbiological information. A common detector or a measuring device (or in abroader sense, an electronic device) other than a biological informationdetector or a biological.

In Patent Citation 1, there is disclosed a pulse rate monitor (or in abroader sense, a biological information measuring device). Alight-receiving element (e.g., a light-receiving element 12 in FIG. 16of Patent Citation 1) of the pulse rate monitor receives light reflectedat a detection site (e.g., dotted line in FIG. 16 of Patent Citation 1)via a diffusion reflection plane (e.g., reflecting part 131 in FIG. 16of Patent Citation 1). In an optical probe 1 in Patent Citation 1 (or ina broader sense, a biological information detector), a light-emittingelement 11 and the light-receiving element 12 overlap in plan view, andthe size of the optical probe is reduced.

JP-A 2004-337605 (Patent Citation 1) is an example of the related art.

SUMMARY Problems to be Solved by the Invention

FIG. 4 in Patent Citation 1 shows an electrode (or in a narrower sense,a bonding pad) and a wiring (or in a narrower sense, a bonding wire) forthe light-receiving element 12. In an instance in which thelight-emitting element 11 and the light-receiving element 12 overlapeach other with respect to a plan view, a first light-emitting element111 of the light-emitting element 11 is positioned directly below thebonding pad, as shown in FIG. 5 of Patent Citation 1. According to aconfiguration described above, when the bonding wire is attached to thebonding pad, it is difficult for the attaching to be made more reliable.Also, the light-emitting element 111 may be damaged during amanufacturing process of such description.

According to several modes of the invention, it is possible to provide amethod for manufacturing an optical device, an optical device, and abiological information detector in which the attaching can be performedmore reliably when a bonding wire is attached to a bonding pad.

Means Used to Solve the Above-Mentioned Problems

A biological information detector in accordance with one aspect of theinvention comprises a substrate, a light-emitting element having athickness of 20 μm to 1000 μm, a light-receiving element having athickness of 20 μm to 1000 μm, and a bonding pad disposed at a positionthat overlaps the light-emitting element and that is displaced relativeto a center of the light-emitting element in a plan view as viewed in aperpendicular direction perpendicular to an emitting surface of thelight-emitting element. A wavelength of light emitted by thelight-emitting element is within a range of 470 nm to 600 nm.

The biological information detector according to the aspect of theinvention further comprises a reflecting part disposed around thelight-emitting element.

In the biological information detector according to the aspect of theinvention, the light-emitting element has a quadrilateral shape in theplan view, and a length of one side of the light-emitting element is 100μm to 10,000 μm.

The biological information detector according to the aspect of theinvention further comprises a light-transmitting film disposed on thesubstrate.

In the biological information detector according to the aspect of theinvention, the maximum transmittance rate of light passing through thelight-transmitting film falls within a range of ±10% of the maximumintensity value of the wavelength of the light emitted by thelight-emitting element.

In the biological information detector according to the aspect of theinvention, the light-transmitting film increases smoothness of a surfaceof the substrate.

In the biological information detector according to the aspect of theinvention, the reflecting part includes metal or resin.

The biological information detector according to the aspect of theinvention further comprises a support part supporting the light-emittingelement, and the support part has a thickness of 50 μm to 1000 μm.

A biological information measuring device comprises the biologicalinformation detector according to the aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are an example of a configuration of an optical deviceaccording to a present embodiment;

FIGS. 2A, 2B, 2C, and 2D are an example of steps according to a methodfor manufacturing the optical device of the present embodiment;

FIG. 3 is a comparative example of an optical device;

FIGS. 4A and 4B are examples of an arrangement of the optical device;

FIGS. 5A and 5B are schematic diagrams showing a distance between afirst center and a second center;

FIGS. 6A and 6B are examples of a configuration of a biologicalinformation detector according to the present embodiment;

FIGS. 7A and 7B are plan views showing the biological informationdetector of FIG. 6A;

FIGS. 8A, 8B, 8C, and 8D are another example of steps according to themethod for manufacturing the optical device of the present embodiment;

FIG. 9 is an example of intensity characteristics of light emitted by alight-emitting element;

FIG. 10 is an example of transmission characteristics of light passingthrough a contact part;

FIG. 11 is another example of a configuration of the biologicalinformation detector according to the present embodiment;

FIG. 12 is an example of transmission characteristics of light passingthrough a substrate coated with a light-transmitting film;

FIGS. 13A, 13B, and 13C are examples of a configuration of a firstreflecting part;

FIGS. 14A and 14B are examples of an outer appearance of the firstreflecting part and the light-emitting element with respect to a planview;

FIGS. 15A and 15B are examples of an outer appearance of a biologicalinformation measuring device comprising the biological informationdetector; and

FIG. 16 is an example of a configuration of the biological informationmeasuring device.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

A description shall now be given for the present embodiment. The presentembodiment described below is not intended to unduly limit the scope ofthe claims of the present embodiment. Not every configuration describedin the present embodiment is necessarily an indispensible constituentfeature of the invention.

1. Optical Device

FIGS. 1A and 1B are an example of a configuration of an optical deviceaccording to a present embodiment. In FIGS. 1A and 1B, the dimensions ofeach of the members are not intended to accurately represent actualdimensions. Specifically, in FIGS. 1A and 1B, the dimensions of each ofthe members have been expanded or reduced in order to facilitateunderstanding of the descriptions given below. Similarly, drawings otherthan FIGS. 1A and 1B are not intended to necessarily represent actualdimensions.

FIG. 1A shows a cross-section view, and FIG. 1B shows a plan view. Asshown in FIG. 1A, the optical device comprises a substrate 11, alight-emitting element 14, and a light-receiving element 16. Thesubstrate 11 has a first surface 11A and a second surface 11B that isopposite the first surface 11A. The light-emitting element 14 isinstalled on the first surface 11B, and the light-receiving element 16is installed on the second surface 11A. As shown, e.g., on FIG. 1B, thelight-emitting element 14 has a first center 14-1 and thelight-receiving element 16 has a second center 16-1 with respect to theplan view.

In the example shown in FIGS. 1A and 1B, the entirety of thelight-emitting element 14 is arranged in a position that completelyoverlaps the light-receiving element 16 with respect to the plan view.However, at least a part of the light-emitting element 14 may bearranged in a position that overlaps the light-receiving element 16 withrespect to the plan view. Specifically, with respect to the plan view,the light-emitting element 14 falls within the light-receiving element16, but a part of the light-emitting element 14 may protrude from thelight-receiving element 16 with respect to the plan view.

Although in the example shown in FIGS. 1A and 1B, both of thelight-emitting element 14 and the light-receiving element 16 are alreadyattached to the substrate 11, in reality, the light-receiving element 16is attached to the substrate 11 in a state in which the light-emittingelement 14 has been attached to the substrate 11. The light-receivingelement 16, which is installed after the light-emitting element 14, hasa bonding pad 16A′. The bonding pad 16A′ is provided at a position thatis displaced relative to the second center 16-1 towards a firstdirection DR1 with respect to the plan view. Also, the first center 14-1is provided at a position that is displaced relative to the secondcenter 16-1 towards a second direction DR2, which is opposite the firstdirection DR1, with respect to the plan view.

The bonding pad 16A′ of the light-receiving element 16 is displacedrelative to a center of the light-receiving element 16 (i.e., the secondcenter 16-1) towards the first direction DR1 with respect to the planview, and a center of the light-emitting element 14 (i.e., the firstcenter 14-1) is displaced relative to the center of the light-receivingelement 14 (i.e., the second center 16-1) towards the second directionDR2 with respect to the plan view. Therefore, when the bonding wire 61-1is attached to the bonding pad 16A′, a position directly below thebonding pad 16A′ can be supported using a jig or a similar tool. Thebonding wire 61-1 can thereby be attached in a reliable manner.

In the example shown in FIGS. 1A and 1B, the bonding wire 61-1 providesan electrical connection between the bonding pad 16A′ of thelight-receiving element 16 and a pad 61′ for providing a connection tothe light-receiving element 16 (or in a broader sense, wiring for thelight-receiving element 16). Also, examples of configurations of theoptical device are not limited by that shown in FIGS. 1A and 1B, and theshape, or a similar attribute, of a part of the example of configuration(e.g., the light-emitting element 14, the light-receiving element 16,the bonding pad 16A′, and other components) may be modified.

1.1 Method for Manufacturing Optical Device

FIGS. 2A, 2B, 2C, and 2D are an example of steps according to a methodfor manufacturing the optical device of the present embodiment. While inthe example shown in FIGS. 1A and 1B, both of the light-emitting element14 and the light-receiving element 16 are already attached to thesubstrate 11, as shown in FIG. 2A, the substrate 11 having a firstsurface 11A and a second surface 11B that is opposite the first surface11A is readied. In an instance in which the first surface 11A refers to,e.g., a front surface, and the second surface 11B refers to, e.g., areverse surface, in the example shown in FIG. 2A, the substrate 11 isupside down.

As shown in FIG. 2B, the light-emitting element 14 is installed on thesecond surface 11B. Then, the substrate 11 to which the light-emittingelement 14 is attached is turned over, and the light-receiving element16 is installed on the first surface 11A. As shown in FIG. 2C, thefollowing conditions (a) through (c) are satisfied (see FIG. 1B).

(a) The light-receiving element 16 having the second center 16-1 and thebonding pad 16A′ overlaps with at least a part of the light-emittingelement 14 with respect to a plan view;

(b) the bonding pad 16A′ is displaced relative to the second center 16-1towards the first direction DR1 with respect to the plan view; and

(c) the first center 14-1 is displaced relative to the second center16-1 towards the second direction DR2 with respect to the plan view.

As shown in FIG. 2 b, a position directly below the bonding pad 16A′ ofthe light-receiving element 16 can be supported by a jig 74. Since theposition directly below the bonding pad 16A′ of the light-receivingelement 16 is being supported, even when the bonding pad 16A′ isrestrained with a bonding tool 72, the bonding pad 16A′ of thelight-receiving element 16 can be immobilized.

FIG. 3 is a comparative example of an optical device. In the exampleshown in FIG. 3, the above-mentioned condition (c) is not satisfied. Asshown in FIG. 3, the jig 74 must provide a space at a position directlybelow the bonding pad 16A′ of the light-receiving element 16 so that thelight-emitting element 14 is not destroyed. Therefore, the positiondirectly below the bonding pad 16A′ of the light-receiving element 16cannot be directly supported by the jig 74. Since the position directlybelow the bonding pad 16A′ of the light-receiving element 16 is notsupported, when the bonding pad 16N is restrained using the bonding tool72, the substrate 11 is caused to bend. The position of the bonding pad16A′ of the light-receiving element 16 changes with the bending of thesubstrate 11. Since the bonding pad 16A′ cannot be immobilized, thebonding wire 61-1 cannot be attached to the bonding pad 16A′ in areliable manner.

In contrast to the example shown in FIG. 3, in the example shown in FIG.2D, the bonding wire 61-1 is attached to the bonding pad 16A′ while theposition directly below the bonding pad 16A′ is supported. Thus, in theexample shown in FIG. 2D, the bonding wire 61-1 can be attached to thebonding pad 16A′ in a reliable manner. As a result, in the method formanufacturing the optical device in which the bonding wire 61-1 isattached to the bonding pad 16A′, the attaching can be performed morereliably.

FIGS. 4A and 4B are examples of an arrangement of the optical device. Aswith FIG. 1B, in the example shown in FIG. 4A and the example shown inFIG. 4B, the light-emitting element 14 and the light-receiving element16 are shown as an optical device. As shown in FIGS. 4A and 4B, thelight-emitting element 14 has a rectangular profile with respect to theplan view, and one side of the rectangle is tangent to a circle having agiven radius and having a center on the bonding pad 16A′ (or in anarrower sense, a center of the bonding pad 16A′) with respect to theplan view. The light-emitting element 14 can be separated, by the givenradius, from the position directly below the bonding pad 16A′ of thelight-receiving element 16. Therefore, a space can he created at theposition directly below the bonding pad 16N of the light-receivingelement 16. For example, as shown, e.g., in FIG. 2D, the substrate 11can be directly supported by the jig 74.

The given radius of the circle having a center on the bonding pad 16Nshown in FIG. 4A is equal to the given radius of the circle having acenter on the bonding pad 16N shown in FIG. 4B, and the light-emittingelement 14 can be separated from the position directly below the bondingpad 16A′ of the light-receiving element 16 by the same given radius.While in the example shown in FIG. 4A, the light-emitting element 14completely overlaps the light-receiving element 16 with respect to theplan view, in the example shown in FIG. 4B, a part of the light-emittingelement 14 overlaps the light-receiving element 16 with respect to theplan view. In an instance in which light emitted by the light-emittingelement 14 is transmitted through the substrate 11 and received by thelight-receiving element 16, the light-emitting element 14 with respectto the plan view forms a light-blocking region, and the light-receivingelement 16 with respect to the plan view also forms a light-blockingregion. In the example shown in FIG. 4A, a light-blocking region as awhole corresponds only to the light-blocking region of thelight-receiving element 16. In the example shown in FIG. 4B, thelight-blocking region as a whole corresponds to, in addition to thelight-blocking region of the light-receiving element 16, thelight-blocking region of the light-emitting element 14 that protrudesfrom the light-blocking region of the light-receiving element 16 (i.e.,the light-blocking region of the light-emitting element 14 that does notoverlap with the light-blocking region of the light-receiving element16). The light-blocking region as a whole in the example shown in FIG.4A is smaller than the light-blocking region as a whole in the exampleshown in FIG. 4B. Therefore, in the example shown in FIG. 4A, light canmore readily reach the light-receiving element 16 compared to theexample shown in FIG. 4B.

FIGS. 5A and 5B are schematic diagrams showing a distance between thefirst center 14-1 and a second center 16-1. As shown in FIGS. 5A and 5B,the light-emitting element 14 has a rectangular (or in a narrower sense,a square) profile with respect to the plan view, and the length of oneside of a square shown in FIG. 5A is equal to the length of one side ofa square shown in FIG. 5B. In the example shown in FIG. 5A, one side(e.g., a side that is nearest to the bonding pad 16A′) of the square (orin a broader sense, a rectangle) is perpendicular to a direction thatconnects the first center 14-1 and the second center 16-1 with respectto the plan view. In the example shown in FIG. 5B, no side, i.e., noneof the four sides, of the square (or in a broader sense, the rectangle)is perpendicular to the direction that connects the first center 14-1and the second center 16-1 with respect to the plan view.

The given radius of the circle having a center on the bonding pad 16A′shown in FIG. 5A can be made smaller than the given radius of the circlehaving a center on the bonding pad 16A′ shown in FIG. 5B. Thus, in aninstance in which one side of the rectangle that represents the profileof the light-emitting element 14 is perpendicular to the direction thatconnects the first center 14-1 and the second center 16-1 with respectto the plan view, the distance between the first center 14-1 and thesecond center 16-1 can be decreased. In an instance in which lightemitted by the light-emitting element 14 is transmitted through thesubstrate 11 and received by the light-receiving element 16, thelight-receiving element 16 can receive light more effectively with ashorter distance between the first center 14-1 and the second center16-1.

2. Biological Information Detector

FIGS. 6A and 6B are examples of a configuration of a biologicalinformation detector according to the present embodiment. As shown inFIGS. 6A and 6B, the biological information detector comprises theoptical device shown, e.g., in FIG. 1A. FIGS. 6A and 6B can also be saidto show other examples of a configuration of the optical deviceaccording to the present embodiment. As shown in FIGS. 6A and 6B, thebiological information detector (or in a broader sense, the opticaldevice) may further comprise a first reflecting part 92. Structures thatare identical to those in the example described above are affixed withthe same numerals, and a description of the structures is not provided.

While in FIG. 6A, the light-emitting element 14 is arranged on a sidetowards a detection site O of a test subject (e.g., a user), in FIG. 6B,the light-receiving element 16 is arranged on a side towards thedetection site O of the test subject. All of the light-receiving element16 and other components arranged on the first surface 11A of thesubstrate 11 in FIG. 6A are arranged on the second surface 11B of thesubstrate 11 in FIG. 6B; however, 16A′ and other numerals shown in FIG.6A are not shown in FIG. 6B. Also, all of the light-emitting element 14and other components arranged on the second surface 11B of the substrate11 in FIG. 6A are arranged on the first surface 11A of the substrate 11in FIG. 6B; however, 14A and other numerals shown in FIG. 6A are notshown in FIG. 6B. Also, the light-emitting element 14 in FIG. 6A emits afirst light R1 and a second light R2; however, the second light R2 isnot shown in FIG. 6B.

The light-emitting element 14 emits light RI directed at the detectionsite O of the test subject (e.g., the user). The light-emitting element14 also emits the second light R2 directed at a direction other thanthat of the detection site O (i.e., directed at the first reflectingpart 92). The first reflecting part 92 reflects the second light R2towards the detection site O. The light-receiving element 16 receiveslight R1′ (i.e., reflected light) having biological information, thelight R1′ being light RI emitted by the light-emitting element 14reflecting at the detection site O. The light-receiving element 16 alsoreceives light R2′ (i.e., reflected light) having biologicalinformation, the light R2′ being the second light R2 reflecting at thedetection site O.

The biological information detector (or in a broader sense, the opticaldevice) may further comprise a second reflecting part 18. In theexamples shown in FIGS. 6A and 6B, the second reflecting part 18reflects the light RI emitted by the light-emitting element 14 or thelight R1′ (i.e., reflected light) having biological information. In theexample shown in FIG. 6A, the second reflecting part 18 reflects thelight R1′ and R2′ (i.e., reflected light) having biological informationfrom the detection site O towards the light-receiving element 16. InFIG. 6B, the second reflecting part 18 reflects the light R1 emitted bythe light-emitting element 14 towards the detection site O. The secondreflecting part 18 may have a reflecting surface on a dome surfaceprovided between the light-emitting element 14 and the light-receivingelement 16.

The biological information detector (or in a broader sense, the opticaldevice) may further comprise a contact part 19. The contact part 19 hasa surface 19A that comes into contact with the test subject, and isformed from a material that is transparent with respect to thewavelength of the light R1 emitted by the light-emitting element 14(e.g., glass). The substrate 11 is also formed from a material that istransparent with respect to the wavelength of the light R1 emitted bythe light-emitting element 14 (e.g., polyimide), and the substrate 11 isformed from, e.g., a flexible substrate.

In the example shown in FIGS. 6A and 6B, the detection site O (e.g., ablood vessel) is within the test subject. The first light R1 travelsinto the test subject and diffuses or scatters at the epidermis, thedermis, and the subcutaneous tissue. The first light R1 then reaches thedetection site O, and is reflected at the detection site O. Thereflected light R1′ reflected at the detection site O diffuses orscatters at the subcutaneous tissue, the dermis, and the epidermis. InFIG. 6A, the reflected light R1′ travels to the reflecting part 18. InFIG. 6B, the first light RI travels to the detection site O via thesecond reflecting part 18. The first light R1 is partially absorbed atthe blood vessel. Therefore, due to an effect of a pulse, the rate ofabsorption at the blood vessel varies, and the amount of the reflectedlight R1′ reflected at the detection site O also varies. Biologicalinformation (e.g. pulse rate) is thus reflected in the reflected lightR1′ reflected at the detection site O.

In FIG. 6A, the second light R2 travels into the test subject, and thereflected light R2′ reflected at the detection site O travels to thesecond reflecting part 18. The biological information (i.e., pulse rate)is also reflected in the reflected light R2′ reflected at the detectionsite O.

Examples of configurations of the biological information detector (or ina broader sense, the optical device) are not limited by those shown inFIGS. 6A and 1B, and the shape, or a similar attribute, of a part of theexample of configuration (e.g., the first reflecting part 92, the secondreflecting part 18, and other components) may be modified. Thebiological information may also be blood oxygen saturation level, bodytemperature, heart rate, or a similar variable; and the detection site Omay be positioned at a surface SA of the test subject. In the exampleshown in FIG. 6A, the first light R1 and the second light R2 are eachshown by a single line, and in the example shown in FIG. 6B, the firstlight R1 is shown by a single line; however, in reality, thelight-emitting element 14 emits many light beams in a variety ofdirections.

In the example shown in FIG. 6A, a part of the wiring for thelight-receiving element 16 is shown, and the pad 61′ for providing aconnection to the light-receiving element 16 is shown. The bonding pad16A′ (or in a broader sense, an electrode) is, e.g., an anode of thelight-receiving element 16. In the example shown in FIG. 6A, aconnecting part 62′ for providing a connection to, e.g., an electrodepad 16C′ (or in a broader sense, an electrode) of the light-receivingelement 16 is also shown as a part of the wiring for the light-receivingelement 16. The electrode pad 16C′ is, e.g., a cathode of thelight-receiving element 16. In the example shown in FIG. 6A, theconnecting part 62′ is directly connected to an electrode pad 16C′.

Also, in the example shown in FIG. 6A, a part of the wiring for thelight-emitting element 14 is shown, and a pad 64′ for providing aconnection to the light-emitting element 14 is shown. The connecting pad64′ is connected to a bonding pad 14A′ (or in a broader sense, anelectrode) of the light-emitting element 14 via a bonding wire 64-1. Thebonding pad 14A′ is, e.g., an anode of the light-emitting element 14.The example shown in FIG. 6A shows a cross-section view corresponding toone cut plane. In the example shown in FIG. 6A, a connecting pad 63′that is not, in reality, present on the cut plane is represented by adotted line. The connecting pad 63′ is connected to a bonding pad 14C′(or in a broader sense, an electrode) of the light-emitting element 14via a bonding wire 63-1. The bonding pad 14C′ is, e.g., a cathode of thelight-emitting element 14.

FIGS. 7A and 7B are plan views showing the biological informationdetector (or in a broader sense, the optical device) of FIG. 6A. FIG. 7Acorresponds to a plan view of a side towards the light-receiving element16, and FIG. 7B corresponds to a plan view of a side towards thelight-emitting element 14. Structures that are identical to those in theexamples described above are affixed with the same numerals, and adescription of the structures is not provided.

In FIG. 7A, each of the light-emitting element 14 and the firstreflecting part 92 is shown by a dotted line. As shown in FIG. 7A, thefirst reflecting part 92 has a third center 92-C, and the third center92-C coincides with the first center 14-1 of the light-emitting element14 with respect to the plan view. In an instance in which the thirdcenter 92-C coincides with the first center 14-1, the first reflectingpart 92 is capable of reflecting light emitted by the light-emittingelement 14 in an efficient manner. The example shown in FIG. 7Asatisfies a positional relationship shown in FIG. 1B. Therefore, thethird center 92-C (i.e., the first center 14-1) is provided at aposition that is displaced, relative to the second center 16-1, towardsthe second direction DR2, which is opposite the first direction DR1,with respect to the plan view.

As shown in FIG. 7A, a wiring 61 for the light-receiving element 16 hasa connecting pad 61′ and the bonding wire 61-1 at one end. Also, awiring 62 for the light-receiving element 16 has the connecting part 62′at one end. As shown in FIG. 7B, a wiring 63 for the light-emittingelement 14 has the connecting pad 63′ and the bonding wire 63-1 at oneend. Also, a wiring 64 for the light-emitting element 14 has theconnecting pad 64′ and the bonding wire 64-1 at one end. Electricalpower can be fed to the light-emitting element 14 from the wiring 63 andthe wiring 64, and an electrical signal from the light-receiving element16 can be extracted from wiring 63 and the wiring 64. In FIG. 7A, thewiring 63 and the wiring 64 are not shown. In FIG. 7B, thelight-receiving element 16 and similar components are each shown by adotted line.

The configuration of the wiring 63 and the wiring 64 for thelight-emitting element 14 and the wiring 61 and the wiring 62 for thelight-receiving element 16 are not limited by the examples shown inFIGS. 7A and 7B. For example, the shape of the connecting pad 61′ of thewiring 61 may, instead of being circular as shown in FIG. 7A, be, e.g.,square, elliptical, polygonal, or describing another shape. The shapeof, e.g., the connecting pad 63′ of the wiring 63 may, instead of beingsquare as shown in FIG. 7B, also be, e.g., circular, elliptical,polygonal, or describing another shape.

2.1 Method for Manufacturing Optical Device in Biological InformationDetector

FIGS. 8A, 8B, 8C, and 8D are another example of steps according to themethod for manufacturing the optical device of the present embodiment.Structures that are identical to those in the examples described aboveare affixed with the same numerals, and a description of the structuresis not provided. The example differs, in general, from the example shownin FIG. 2D in that the light-emitting element 14 is installed on thesecond surface 11B with the first reflecting part 92 for reflectinglight emitted by the light-emitting element 14 interposed therebetween,and the bonding wire 61-1 is attached to the bonding pad 16A′ while theposition directly below the bonding pad 16A′ is supported by the firstreflecting part 92 (FIG. 8D).

Adding the first reflecting part 92 to the light-emitting element 14makes it possible to support the position directly below the bonding pad16A′ of the light-receiving element 16 using the first reflecting part92 and the jig 74 or a similar tool. Therefore, the bonding wire 16-1can be attached to the bonding pad 16A′ in a reliable manner. Also, thefirst reflecting part 92 makes it possible to prevent the jig 74 fromcoming into contact with the light-emitting element 14, and as a result,it is possible to prevent the light-emitting element 14 from beingdamaged.

As shown in FIGS. 8A, 6A, and 7B, the connecting pad 64′ and theconnecting pad 63′ (or in a broader sense, the wirings 64, 63 for thelight-emitting element 14) are arranged in advance on the second surface11B of the substrate 11. Also, the connecting pad 61′ and the connectingpart 62′ (or in a broader sense, the wirings 61, 62 for thelight-receiving element 16) are arranged in advance on the first surface11A of the substrate 11.

As shown in FIG. 8B, the first reflecting part 92, to which thelight-emitting element 14 has been attached in advance, is arranged onthe second surface 11B of the substrate 11, and the bonding wire 64-1 isattached to the bonding pad 14A′ while the first surface 11A of thesubstrate 11 is supported a jig or a similar tool (not shown). Also, thebonding wire 63-1 is attached to the bonding pad 14C′.

As shown in FIG. 8C, the following conditions (a) through (c) aresatisfied.

(a) The light-receiving element 16 having the second center 16-1 and thebonding pad 16A′ overlaps with at least a part of the light-emittingelement 14 with respect to the plan view;

(b) the bonding pad 16A′ is displaced relative to the second center 16-1towards the first direction DR1 with respect to the plan view; and

(c) the third center 92-C (and the first center 14-1) are displacedrelative to the second center 16-1 towards a second direction DR2 withrespect to the plan view.

As shown in FIG. 8C, when a wire bonding step in the optical device iscomplete, the second reflecting part 18 and the contact part 19 areattached to the substrate 11 as shown, e.g., in FIG. 6A.

As shown in FIG. 6A or FIG. 6B, the substrate 11 is arranged between thesecond reflecting part 18 and the contact part 19. Therefore, even in aninstance in which the light-emitting element 14 and the light-receivingelement 16 are arranged on the substrate 11, there is no need toseparately provide a mechanism for supporting the substrate 11 itself,and the number of components is smaller. Also, since the substrate 11 isformed from a material that is transparent with respect to the emissionwavelength, the substrate 11 can be arranged on a light path from thelight-emitting element 14 to the light-receiving element 16, and thereis no need to accommodate the substrate 11 at a position away from thelight path, such as within the second reflecting part 18. A biologicalinformation detector (or in a broader sense, an optical device) that canbe readily assembled can thus be provided. Also, the second reflectingpart 18 is capable of increasing the amount of light reaching thelight-receiving element 16 or the detection site O, and the detectionaccuracy (i.e., the signal-to-noise ratio) of the biological informationdetector increases.

In Patent Citation 1, it is necessary to install the light-emittingelement 11, the light-receiving element 12, the substrate 15, and thetransparent material 142 in the interior of the reflecting part 131.Therefore, a small optical probe 1 cannot be assembled with ease. Also,according to paragraph [0048] in Patent Citation 1, the substrate 15 isformed so that an interior-side of the reflecting part 131 is a diffusereflection surface. In other words, the substrate 15 in Patent Citation1 is not required to be formed from a transparent material.

The thickness of the substrate 11 is e.g., 10 μm to 1000 μm. Thesubstrate 11 is, e.g., a printed circuit board; however, a printedcircuit board is not generally formed from a transparent material, aswith the substrate 15 of Patent Citation 1. Specifically, the inventorspurposefully used a configuration in which the printed circuit board isformed from a material that is transparent at least with respect to theemission wavelength of the light-emitting element 14. The thickness ofthe contact part 19 is, e.g., 1 μm to 3000 μm.

The light-emitting element 14 is, e.g., an LED. The light emitted by theLED has a maximum intensity (or in a broader sense, a peak intensity)within a wavelength range of, e.g., 425 nm to 625 nm, and is, e.g.,green in color. The thickness of the light-emitting element 14 is, e.g.,20 μm to 1000 μm. The light-receiving element 16 is, e.g., a photodiode,and can generally be formed by a silicon photodiode. The thickness ofthe light-receiving element 16 is, e.g., 20 μm to 1000 μm. The siliconphotodiode has a maximum sensitivity (or in a broader sense, a peaksensitivity) for received light having a wavelength within a range of,e.g., 800 nm to 1000 nm. Ideally, the light-receiving element 16 isformed by a gallium arsenide phosphide photodiode, and the galliumarsenide phosphide photodiode has a maximum sensitivity (or in a broadersense, a peak sensitivity) for received light having a wavelength withina range of, e.g., 550 nm to 650 nm. Since biological substances (wateror hemoglobin) readily allow transmission of infrared light within awavelength range of 700 nm to 1100 nm, the light-receiving element 16formed by the gallium arsenide phosphide photodiode is more capable ofreducing noise components arising from external light than thelight-receiving element 16 formed by the silicon photodiode.

FIG. 9 shows an example of intensity characteristics of the lightemitted by the light-emitting element 14. In the example shown in FIG.9, the intensity is at a maximum for light having a wavelength of 520nm, and the intensity of light having other wavelengths is normalizedwith respect thereto. Also, in the example shown in FIG. 9, thewavelengths of light emitted by the light-emitting element 14 are withina range of 470 nm to 600 nm.

FIG. 10 shows an example of transmission characteristics of lightpassing through the contact part 19. As shown in FIG. 10, at thewavelength of light (520 nm) emitted by the light-emitting element 14 atwhich the intensity is at a maximum shown, e.g., in FIG. 9, thetransmittance is 50% or above. Also, although an example of transmissioncharacteristics of light passing through the substrate 11 itself is notshown, transmittance of the substrate 11 with respect to a wavelength of520 nm can be set to, e.g., 50% or above, as with the transmissioncharacteristics shown in FIG. 10. The contact part 19 and the substrate11 can be formed from a material that is transparent with respect to thewavelength of light R1 emitted by the light-emitting element 14.

FIG. 11 is another example of a configuration of the biologicalinformation detector according to the present embodiment. As shown inFIG. 11, the light-transmitting film 11-1 can be formed on the firstsurface 11A and the second surface 11B, which is opposite the firstsurface, of the substrate 11. Structures that are identical to those inthe example described above are affixed with the same numerals, and adescription of the structures is not provided. The light-transmittingfilm 11-1 may be formed only on the first surface 11A, or may be formedonly on the second surface 11B. Also, in the example shown in FIG. 11,the light-transmitting film 11-1 is formed on a light-transmittingregion of the substrate 11 on which the light-emitting element 14 andthe light-receiving element 16 (or in a narrower sense, the firstreflecting part 92, the connecting pad 64′ (i.e., wirings 63, 64 for thelight-emitting element 14 in FIG. 7B), the connecting part 62′, and theconnecting pad 61′ (i.e., wirings 61, 62 for the light-receiving element16 in FIG. 7B)) are not arranged. Although FIG. 11 corresponds to FIG.6A, the light-transmitting film 11-1 may be formed on at least one ofthe first surface 11A and the second surface 11B of the substrate 11 inFIG. 6B. The light-transmitting film 11-1 may be formed from, e.g., asolder resist (or in a broader sense, a resist).

In the example shown in FIG. 11, the first surface 11A and the secondsurface 11B of the substrate 11 may be processed so as to form a roughsurface so that the wirings 61, 62, 63, 64 (including the connectingpads 61′, 64′, the connecting part 62′, and similar components) on thesubstrate 11 do not peel off. Therefore, the light-transmitting film11-1 is formed on the first surface 11A and the second surface 11B,whereby the roughness on the surface of the substrate 11 is filled withthe light-transmitting film, and the smoothness of the entire substrate11 is increased. Specifically, the light-transmitting film 11-1 on thesubstrate 11 is smooth, and can therefore reduce dispersion of light onthe roughness on the surface of the substrate 11 during transmission ofthe light through the substrate 11. Specifically, the presence of thelight-transmitting film 11-1 increases the transmittance of thesubstrate 11. Therefore, the amount of light reaching thelight-receiving element 16 or the detection site O increases, and thedetection accuracy of the biological information detector increasesfurther.

The refractive index of the light-transmitting film 11-1 is preferablybetween the refractive index of air and the refractive index of thesubstrate 11. Further preferably, the refractive index of thelight-transmitting film 11-1 is preferably closer to the refractiveindex of the substrate 11 than the refractive index of air. In such aninstance, it is possible to reduce reflection of light on an interface.

FIG. 12 is an example of transmission characteristics of light passingthrough the substrate 11 coated with a light-transmitting film. In theexample shown in FIG. 12, transmittance is calculated using theintensity of light before being transmitted through the substrate 11 andthe intensity of light after being transmitted through the substrate 11.In the example shown in FIG. 12, in the range of wavelength the equal toor less than 700 nm, which is the lower limit of the optical window inbiological tissue, the transmittance is at a maximum for light having awavelength of 525 nm. Or, in the example shown in FIG. 12, in the rangeof wavelength equal to or less than 700 nm, which is the lower limit ofthe optical window in biological tissue, the wavelength of the maximumtransmittance of light passing through the light transmission film 11-1falls within a range of ±10% of the wavelength of the maximum intensityof light generated by the light-emitting part 14 in FIG. 9, for example.It is preferable that the light-transmitting film 11-1 thus selectivelytransmit light generated by the light-emitting element 14 (e.g., thefirst light R1 (or in a narrower sense, the reflected light R1′ producedby the first light R1 being reflected) in FIG. 6A). The presence of thelight-transmitting film 11-1 makes it possible to enhance the smoothnessof the substrate 11 and prevent, to a certain extent, a decrease inefficiency of the light-emitting element 14 and the light-receivingelement 16. In an instance in which transmittance has a maximum value(or in a broader sense, a peak value) within, e.g., a visible lightregion for light having a wavelength of 525 nm, as shown in the examplein FIG. 12, the light-transmitting film 11-1 is, e.g., green.

In the example shown in FIG. 6A, the light-emitting element 14 may havea first light-emitting surface 14A that faces the detection site O andemits the first light R1. The light-emitting element 14 may also have asecond light-emitting surface 14B that is a side surface of the firstlight-emitting surface 14A and emits the second light R2. In such aninstance, the first reflecting part 92 may have a wall part thatsurrounds the second light-emitting surface 14B.

FIGS. 13A, 13B, and 13C are examples of a configuration of the firstreflecting part 92 shown in FIG. 6A. As shown in FIG. 13A, the firstreflecting part 92 may have a support part 92-1 for supporting thelight-emitting element 14, and an inner wall surface 92-2 and a topsurface 92-3 of the wall part surrounding the second light-emittingsurface 14B of the light-emitting element 14. The light-emitting element14 is not shown in FIGS. 13A through 13C. In the example shown in FIG.13A, the first reflecting part 92 can reflect the second light R2 on theinner wall surface 92-2 towards the detection site O (see FIG. 6A), thefirst reflecting part 92 having a first reflecting surface on the innerwall surface 92-2. The thickness of the support part 92-1 is, e.g., 50μm to 1000 μm, and the thickness of the wall part (92-3) is, e.g., 100μm to 1000 μm.

In the example shown in FIG. 13A, the inner wall surface 92-2 has aninclined surface (92-2) which, with increasing distance in a widthdirection (i.e., a first direction) from a center of the firstreflecting part 92, inclines towards the detection site O in a heightdirection (i.e., a direction that is perpendicular to the firstdirection), in cross-section view. The inclined surface (92-2) in FIG.13A is formed by, in cross-section view, an inclined plane, but may alsobe a curved surface shown in, e.g., FIG. 13C, or a similar inclinedsurface. The inner wall surface 92-2 may also be formed as a pluralityof inclined flat surfaces whose angle of inclination vary from oneanother, or by a curved surface having a plurality of curvatures. In aninstance in which the inner wall surface 92-2 of the first reflectingpart 92 has an inclined surface, the inner wall surface 92-2 of thefirst reflecting part 92 is capable of reflecting the second light R2towards the detection site O. In other words, the inclined surface onthe inner wall surface 92-2 of the first reflecting part 92 can be saidto be the first reflecting surface for improving the directivity of thelight-emitting element 14. In such an instance, the amount of lightreaching the detection site O increases further. The top surface 92-3shown in FIGS. 13A and 13C may be omitted as shown, e.g., in FIG. 13B.In an instance in which the first reflecting part 92 has the top surface92-3, the top surface 92-3 may be supported by the jig 74 (see FIG. 8D).In FIGS. 13A through 13C, a range indicated by label 92-4 function as amirror surface part.

FIGS. 14A and 14B respectively show an example of an outer appearance ofthe first reflecting part 92 and the light-emitting element 14 of FIG.6A in plan view. In the example shown in FIG. 14A, with respect to theplan view (when viewed from, e.g., towards the detection site O shown inFIG. 6A), an outer circumference of the first reflecting part 92 iscircular, where the diameter of the circle is, e.g., 200 μm to 11,000μm. In the example shown in FIG. 14A, the wall part (92-2) of the firstreflecting part 92 surrounds the light-emitting element 14 (see FIG.6A). The outer circumference of the first reflecting part 92 may also bea quadrilateral (or specifically, a square) with respect to the planview as shown, e.g., in FIG. 14B. Also, in the examples shown in FIGS.14A and 14B, with respect to the plan view (when viewed from, e.g.,towards the detection site O shown in FIG. 6A), the outer circumferenceof the light-emitting element 14 is a quadrilateral (or specifically, asquare), where the length of one side of the square is, e.g., 100 μm to10,000 μm. The outer circumference of the light-emitting element 14 mayalso be circular.

The first reflecting part 92 is made of metal whose surface is polishedto a mirror finish, and thereby has a reflective structure (orspecifically, a mirror reflection structure). The first reflecting part92 may also be formed from, e.g., a resin whose surface is polished to amirror finish. Specifically, for example, a base metal forming a base ofthe first reflecting part 92 is readied, and a surface of the base metalis then, e.g., subjected to plating. Alternatively, a mold of the firstreflecting part 92 (not shown) is filled with a thermoplastic resin,molding is performed, and a metal film, for example, is then depositedby vapor deposition on a surface of the mold.

In the examples shown in FIGS. 14A and 14B, in plan view (when viewedfrom, e.g., towards the detection site O shown in FIG. 6A), a region ofthe first reflecting part 92 other than that directly supporting thelight-emitting element 14 (i.e., the inner wall surface 92-2 and the topsurface 92-3 of the wall part, and a part of the support part 92-1) isexposed. The exposed region is shown as a mirror surface part 92-4 inFIG. 13A. Although in the example shown in FIG. 13A, a dotted linerepresenting the mirror surface part 92-4 is shown within the firstreflecting part 92, the mirror surface part 92-4 is actually formed on asurface of the first reflecting part 92.

In the examples shown in FIGS. 13A, 13B, and 13C, the mirror surfacepart 92-4 preferably has a high reflectivity. The reflectivity of themirror surface part 92-4 is, e.g., 80% to 90% or higher. It is possiblefor the mirror surface part 92-4 to be formed only on the inclinedsurface of the inner wall surface 92-2. In an instance in which themirror surface part 92-4 is formed not only on the inclined surface ofthe inner wall surface 92-2 but also on the support part 92-1, thedirectivity of the light-emitting element 14 increases further.

The second reflecting part 18 is formed from, e.g., a resin whosesurface (i.e., a reflecting surface on a side towards thelight-receiving element 16 in FIG. 6A) is polished to a mirror finish,and thereby has a reflective structure (or specifically, a mirrorreflection structure). In other words, the second reflecting part 18 iscapable of causing mirror reflection of light without causing diffusereflection of light. In an instance in which the second reflecting part18 has a mirror reflection structure, the second reflecting part 18 isalso capable of not causing reflected light R1″ (i.e., directlyreflected light; invalid light) produced by reflection of the firstlight R1 to reflect towards the light-receiving element 16, thereflected light R1″ having a reflection angle that is different to thatof the reflected light R1′ produced by reflection of the first light R1(see FIG. 6A). In such an instance, the detection accuracy of thebiological information detector is further increased. As shown in FIG.6A, since the reflected light R1′ produced by reflection of the firstlight R1 originates from the detection site O, which is within the testsubject, the reflection angle of the reflected light R1′ produced byreflection of the first light R1 (i.e., a reflection angle relative to astraight line perpendicular to the surface SA of the test subject) isgenerally small. Meanwhile, since the reflected light R1″ produced byreflection of the first light R1 originates from the surface SA of thetest subject, the reflection angle of the reflected light R1″ producedby reflection of the first light R1 is generally large.

In FIG. 16 of Patent Citation 1, there is disclosed a reflecting part131; and according to paragraphs [0046], [0059], and [0077] in PatentCitation 1, the reflecting part 131 has a diffuse reflection structure,and the reflectivity is increased to improve the efficiency of thelight-receiving element 12. However, at the time of filing, it had notbeen recognized by those skilled in the art that in the reflecting part131 according to Patent Citation 1, directly reflected light (or in abroader sense, noise) is also reflected towards the light-receivingelement 12. In other words, the inventors recognized that reducing anoise component arising from the directly reflected light from a lightreception signal increases the efficiency of the light-receivingelement. Specifically, the inventors recognized that the detectionaccuracy of the biological information detector is further increased inan instance in which the second reflecting part 18 has a mirrorreflection structure.

3. Biological Information Measuring Device 3.1 Pulse Rate Monitor

FIGS. 15A and 15B are examples of the outer appearance of a biologicalinformation measuring device comprising the biological informationdetector such as that shown in FIG. 1 and other drawings. As shown inFIG. 15A, the biological information detector shown, e.g., in FIG. 6Amay further comprise a wristband 150 capable of attaching the biologicalinformation detector to an arm (or specifically, a wrist) of the testsubject (i.e., the user). In the example shown in FIG. 15A, thebiological information is the pulse rate indicated by, e.g., “72.” Thebiological information detector is installed in a wristwatch showing thetime (e.g., “8:15 am”). As shown in FIG. 15B, an opening part isprovided to a back cover of the wristwatch, and the contact part 19shown in, e.g., FIG. 6A is exposed in the opening part. In the exampleshown in FIG. 15B, the second reflecting part 18 and the light-receivingelement 16 are installed in a wristwatch. In the example shown in FIG.15B, the first reflecting part 92, the light-emitting element 14, thewristband 150, and other components are not shown.

FIG. 16 is an example of a configuration of the biological informationmeasuring device. The biological information measuring device includesthe biological information detector as shown, e.g., in FIG. 6A, and abiological information measuring part for measuring biologicalinformation from a light reception signal generated at thelight-receiving element 16 of the biological information detector. Asshown in FIG. 16, the biological information detector may have thelight-emitting element 14, the light-receiving element 16, and a circuit161 for controlling the light-emitting element 14. The biologicalinformation detector may further have a circuit 162 for amplifying thelight reception signal from the light-receiving element 16. Thebiological information measuring part may have an A/D conversion circuit163 for performing A/D conversion of the light reception signal from thelight-receiving element 16, and a pulse rate computation circuit 164 forcalculating the pulse rate. The biological information measuring partmay further have a display part 165 for displaying the pulse rate.

The biological information detector may have an acceleration detectingpart 166, and the biological information measuring part may further havean A/D conversion circuit 167 for performing A/D conversion of anacceleration signal from the acceleration detecting part 166 and adigital signal processing circuit 168 for processing a digital signal.The configuration of the biological information measuring device is notlimited to the example shown in FIG. 16. The pulse rate computationcircuit 164 in FIG. 16 may be, e.g., an MPU (i.e., a micro processingunit) of an electronic device installed with the biological informationdetector.

The control circuit 161 in FIG. 16 drives the light-emitting element 14.The control circuit 161 is, e.g., a constant current circuit, delivers apredetermined voltage (e.g., 6 V) to the light-emitting element 14 via aprotective resistance, and maintains a current flowing to thelight-emitting element 14 at a predetermined value (e.g., 2 mA). Thecontrol circuit 161 is capable of driving the light-emitting element 14in an intermittent manner (e.g. at 128 Hz) in order to reduceconsumption current. The control circuit 161 is formed on, e.g., amotherboard, and wiring between the control circuit 161 and thelight-emitting element 14 is formed, e.g., on the substrate 11 shown inFIG. 6A.

The amplification circuit 162 shown in FIG. 16 is capable of removing aDC component from the light reception signal (i.e., an electricalcurrent) generated in the light-receiving element 16, extracting only anAC component, amplifying the AC component, and generating an AC signal.The amplification circuit 162 removes the DC component at or below apredetermined wavelength using, e.g., a high-pass filter, and buffersthe AC component using, e.g., an operational amplifier. The lightreception signal contains a pulsating component and a body movementcomponent. The amplification circuit 162 or the control circuit 161 iscapable of feeding a power supply voltage for operating thelight-receiving element 16 at, e.g., reverse bias to the light-receivingelement 16. In an instance in which the light-emitting element 14 isintermittently driven, the power supply to the light-receiving element16 is also intermittently fed, and the AC component is alsointermittently amplified. The amplification circuit 162 is formed on,e.g., the mother board, and wiring between the amplification circuit 162and the light-receiving element 16 is formed on, e.g., the substrate 11shown in FIG. 6A. The amplification circuit 162 may also have anamplifier for amplifying the light reception signal at a stage prior tothe high-pass filter. In an instance in which the amplification circuit162 has an amplifier, the amplifier is formed, e.g., on the substrate11.

The A/D conversion circuit 163 shown in FIG. 16 converts an AC signalgenerated in the amplification circuit 162 into a digital signal (i.e.,a first digital signal). The acceleration detecting part 166 shown inFIG. 16 calculates, e.g., acceleration in three axes (i.e., x-axis,y-axis, and z-axis) and generates an acceleration signal. Movement ofthe body (i.e., the arm), and therefore movement of the biologicalinformation measuring device, are reflected in the acceleration signal.The A/D conversion circuit 167 shown in FIG. 16 converts theacceleration signal generated in the acceleration detecting part 166into a digital signal (i.e., a second digital signal).

The digital signal processing circuit 168 shown in FIG. 16 uses thesecond digital signal to remove or reduce the body movement component inthe first digital signal. The digital signal processing circuit 168 maybe formed with, e.g., an FIR filter or another adaptive filter. Thedigital signal processing circuit 168 inputs the first digital signaland the second digital signal into the adaptive filter and generates afilter output signal in which noise has been removed or reduced.

The pulse rate computation circuit 164 shown in FIG. 16 uses e.g. fastFourier transform (or in a broader sense, discrete Fourier transform) toperform a frequency analysis on the filter output signal. The pulse ratecomputation circuit 164 identifies a frequency that represents apulsating component based on a result of the frequency analysis, andcalculates a pulse rate.

3.2 Pulse Oximeter

A description will now be given for a pulse oximeter as another exampleof the biological information measuring device. A biological informationdetector (or in a broader sense, an optical device) that is installed inthe pulse oximeter can be obtained using a configuration that isidentical to that used in the above-described embodiment (i.e., theconfiguration shown in, e.g., FIG. 6A or FIG. 1A).

A description will now be given based on the configuration shown in FIG.6A. The pulse oximeter (or in a broader sense, the biologicalinformation detector) comprises the light-emitting element 14 and thelight-receiving element 16. The light-emitting element 14 emits, e.g., ared light and infrared light. Reflected light, produced by the lightemitted by the light-emitting element 14 reflecting at the detectionsite O (e.g., a blood vessel), is measured using the light-receivingelement 16. Red-light and infrared absorbance of haemoglobin in theblood differ depending on presence of a bond with oxygen. Therefore, thearterial oxygen saturation (S_(p)O₂) can be measured by measuring thereflected light at the light-receiving element 16 and analyzing thereflected light.

The configuration of the biological information measuring part (i.e.,the A/D conversion circuit 163, the pulse rate computation circuit 164,the display part 165, the acceleration detecting part 166, the A/Dconversion circuit 167, and the digital signal processing circuit 168)for use in a pulse rate monitor as shown in FIG. 16 can be used as aconfiguration of the biological information measuring part for use inthe pulse oximeter. However, the pulse rate computation circuit 164shown in FIG. 16 is replaced by an arterial oxygen saturation analysiscircuit 164 in which a pulse rate computation circuit and an FFT oranother approach is used.

Although a detailed description was made concerning the presentembodiment as stated above, persons skilled in the art should be able toeasily understand that various modifications can be made withoutsubstantially departing from the scope and effects of the invention.Accordingly, all of such examples of modifications are to be included inthe scope of the invention. For example, terms stated at least oncetogether with different terms having broader sense or identical sense inthe specification or drawings may be replaced with those different termsin any and all locations of the specification or drawings.

A first aspect of the embodiment relates to a method for manufacturingan optical device, comprises:

readying a substrate having a first surface and a second surface that isopposite the first surface;

installing on the second surface a light-emitting element having a firstcenter;

installing a light-receiving element having a second center and abonding pad so that

(a) the light-receiving element overlaps with at least a part of thelight-emitting element with respect to a plan view;

(b) the bonding pad is displaced relative to the second center towards afirst direction with respect to the plan view; and

(c) the first center is displaced relative to the second center towardsa second direction, which is opposite the first direction, with respectto the plan view; and

attaching a bonding wire to the bonding pad while supporting a positiondirectly below the bonding pad.

According to the first aspect of the embodiment, the bonding pad of thelight-receiving element is displaced relative to a center of thelight-receiving element (i.e., the second center) towards the firstdirection with respect to the plan view, and a center of thelight-emitting element (i.e., the first center) is displaced relative tothe center of the light-receiving element (i.e., the second center)towards the second direction with respect to the plan view. Therefore,the position directly below the bonding pad of the light-receivingelement can be supported using a jig or a similar tool. Since a positiondirectly below the bonding pad of the light-receiving element issupported, the bonding pad of the light-receiving element can beimmobilized even when the bonding pad is restrained with a bonding tool.The bonding wire can thereby be reliably attached to the bonding pad. Asa result, when the bonding wire is attached to the bonding pad, theattaching can be performed more reliably. In an instance in which aspace is created in the position directly below the bonding pad of thelight-receiving element, it is possible to avoid installing thelight-emitting element in the position directly below the bonding pad ofthe light-receiving element. Therefore, it is possible to prevent thelight-emitting element from being damaged when the bonding wire isattached to the bonding pad.

According to a second aspect of the embodiment,

the light-emitting element may be installed on the second surface with afirst reflecting part interposed between, the first reflecting partadapted for reflecting light emitted by the light-emitting element and

the bonding wire may be attached to the bonding pad while the positiondirectly below the bonding pad is supported by the first reflectingpart.

Thus, adding the first reflecting part to the light-emitting elementmakes it possible to support the position directly below the bonding padof the light-receiving element using the first reflecting part and a jigor a similar tool. Therefore, the bonding wire can be attached to thebonding pad in a reliable manner. Also, the first reflecting part makesit possible to prevent the jig from coming into contact with thelight-emitting element, and as a result, it is possible to prevent thelight-emitting element from being damaged.

A third aspect of the embodiment relates to an optical device,characterized in comprising:

a substrate having a first surface and a second surface that is oppositethe first surface;

a light-emitting element having a first center, the light-emittingelement being installed on the second surface; and

a light-receiving element having a second center, the light-receivingelement being installed on the first surface; wherein

at least a part of the light-emitting element is arranged at a positionthat overlaps the light-receiving element with respect to a plan view;

the light-receiving element installed subsequent to the light-emittingelement has a bonding pad;

the bonding pad is provided at a position that is displaced relative tothe second center towards a first direction with respect to the planview; and

the first center is provided at a position that is displaced relative tothe second center towards a second direction, which is opposite thefirst direction, with respect to the plan view.

According to the third aspect of the embodiment, the bonding pad of thelight-receiving element is provided to the position that is displacedrelative to a center of the light-receiving element (i.e., the secondcenter) towards the first direction with respect to the plan view, and acenter of the light-emitting element (i.e., the first center) isdisplaced relative to the center of the light-receiving element (i.e.,the second center) towards the second direction with respect to the planview. Therefore, the bonding wire can be attached to the bonding pad ina reliable manner.

According to a fourth aspect of the embodiment,

the light-emitting element may have a rectangular profile with respectto the plan view; wherein

one side of the rectangle may be tangent to a circle having a givenradius and having a center on the bonding pad with respect to the planview.

Thus, the light-emitting element may be separated from the positiondirectly below the bonding pad of the light-receiving element by thegiven radius. Therefore, a space can be created at the position directlybelow the bonding pad of the light-receiving element.

According to a fifth aspect of the embodiment,

the light-emitting element may have a rectangular profile with respectto the plan view; wherein

one side of the rectangle may be perpendicular to a direction in whichthe first center and the second center are connected, with respect tothe plan view.

Thus, the light-emitting element can be separated from the positiondirectly below the bonding pad of the light-receiving element in aneffective manner. Therefore, a space can be created at the positiondirectly below the bonding pad of the light-receiving element.

According to a sixth aspect of the embodiment, the entirety of thelight-emitting element may be arranged at a position at which there is acomplete overlapping of the light-receiving element with respect to theplan view.

Thus, the light-emitting element completely overlaps the light-receivingelement with respect to the plan view, and whereby light can readilyreach the light-receiving element. Specifically, a light-blocking regionformed by the light-emitting element overlaps a light-blocking regionformed by the light-receiving element, and a light-blocking region as awhole corresponds only to the light-blocking region formed by thelight-receiving element.

According to a seventh aspect of the embodiment, the optical device mayfurther comprise a first reflecting part for reflecting light emitted bythe light-emitting element, the first reflecting part having a thirdcenter, wherein the third center may coincide with the first center withrespect to the plan view.

Thus adding the first reflecting part to the light-emitting elementmakes it possible to support the position directly below the bonding padof the light-receiving element with the first reflecting part and a jigor a similar tool. Therefore, the bonding wire can be attached to thebonding pad in a reliable manner.

An eighth aspect of the embodiment relates to a biological informationdetector, characterized in comprising:

the optical device described above;

a contact part formed from a material that is transparent with respectto a wavelength of light emitted by the light-emitting element, thecontact part having a contact surface in contact with a test subject;and

a second reflecting part for reflecting light having biologicalinformation; wherein

the light-emitting element emits light directed at a detection site ofthe test subject;

the light-receiving element receives light having biologicalinformation, the light being light emitted by the light-emitting elementand reflected at the detection site;

the substrate is a flexible substrate formed from a material that istransparent with respect to the wavelength of light emitted by thelight-emitting element; and

the biological information is a pulse rate.

According to the eighth aspect, applying an optical device to abiological information detector makes it possible to provide abiological information detector (i.e., a pulse rate monitor) in which,when the bonding wire is attached to the bonding pad, the attaching canbe performed.

The entire disclosure of Japanese Patent Application No. 2010-33058,filed Feb. 18, 2010 is expressly incorporated by reference herein.

1. A biological information detector comprising: a substrate; alight-emitting element having a thickness of 20 μm to 1000 μm; alight-receiving element having a thickness of 20 μm to 1000 μm; and abonding pad disposed at a position that overlaps the light-emittingelement and that is displaced relative to a center of the light-emittingelement in a plan view as viewed in a perpendicular directionperpendicular to an emitting surface of the light-emitting element, awavelength of light emitted by the light-emitting element being within arange of 470 nm to 600 nm.
 2. The biological information detectoraccording to claim 1, further comprising a reflecting part disposed inperiphery of the light-emitting element.
 3. The biological informationdetector according to claim 1, wherein the light-emitting element has aquadrilateral shape in the plan view, and a length of one side of thelight-emitting element is 100 μm to 10,000 μm.
 4. The biologicalinformation detector according to claim 1, further comprising alight-transmitting film disposed on the substrate.
 5. The biologicalinformation detector according to claim 4, wherein the maximumtransmittance rate of light passing through the light-transmitting filmfalls within a range of ±10% of the maximum intensity value of thewavelength of the light emitted by the light-emitting element.
 6. Thebiological information detector according to claim 4, wherein thelight-transmitting film increases smoothness of a surface of thesubstrate.
 7. The biological information detector according to claim 2,wherein the reflecting part includes metal or resin.
 8. The biologicalinformation detector according to claim 1, further comprising: a supportpart supporting the light-emitting element, the support part having athickness of 50 μm to 1000 μm.
 9. A biological information measuringdevice comprising: the biological information detector according toclaim 1.